The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section. Furthermore, all embodiments are not necessarily intended to solve all or even any of the problems brought forward in this section.
During the drilling of a well or during the “open hole” period of the drilled well, it may be advantageous to characterize, in real time, the gas (or more generally the fluid) in the well.
For instance, it may be interesting to determine the proportion of each cut of C1-C30 in the fluid (i.e. molecules that have 1 to 30 carbon atoms).
If it is possible to determine the individual proportion and characteristic of each cut C1-C30 in a given fluid in laboratories, no industrial method/device may be used in a well to determine such proportions and characteristics for each of them.
For instance, mud gas measurements (e.g. “Gas While Drilling” or GWD) have a sufficient level of reliability to consider that the composition of the cuts C1 to C5 (eventually C6) may be determined all along the well. Nevertheless, no individual information regarding the cuts above C6, i.e. Ci>6 cuts (i.e. molecules with i carbons, i being strictly higher than 6) may be drawn from GWD measurements: such measurements are limited to the light end of the fluid and, consequently, cannot provide straightforward conclusions on the fluid nature and properties.
In addition, “Downhole Fluid Analysis” (or DFA, which is a measurement method based mainly on optical analysis of the fluid at given coordinates in the well) may provide real time measurements of fluid properties while pumping out the reservoir fluid at selected stations (i.e. at selected elevation values). These DFA methods provide information on composition of groups of molecules, for instance, the group of C1, the group of C2-C5 or the group of C6+ (i.e. the molecules with 6 or more than 6 carbons). DFA methods also provide GOR (for “Gas oil ratio”) and live downhole fluid density. Nevertheless, no individual information regarding the individual cuts above C6, i.e. Ci>6 cuts (i.e. molecules with i carbons, i being strictly higher than 6) may be drawn from DFA measurements: DFA only provide the grouped weight concentration of the C6+ group.
In brief, the mud gas service (GWD) cannot quantify full cuts heavier than C6 and optical fluid techniques (DFA) only deliver a lumped C6+ cut at selected stations (i.e. at selected elevation values).
Based on this sparse set of data (C1 to C5 and C1, C2-C5, C6+), there is a need to determine information on higher full cuts (for instance, C7, . . . , C30) in a thermodynamically consistent and vertically continuous approach.